In the technical sector relating to the manufacture of switchboards for the wiring of electrical installations, terminal blocks can be used that are designed to be mounted on corresponding support rails and to provide frontal access to the means—typically of the screw type—for retaining the electrical connection wires that form the electric circuit. The increasing complexity of electric switchboards can result in the need to provide each terminal block with a corresponding identification label that should be frontally visible so that it can be read by the user.